Chuck device

ABSTRACT

A chuck device ( 1 ) includes: a worm gear mechanism ( 5 ) decelerating a rotational drive force applied through an input shaft member ( 4 ); a second gear mechanism ( 6 ) using the rotational drive force transferred from the worm gear mechanism ( 5 ) to drive a screw shaft member ( 46 ) in the axial direction; and a conversion mechanism ( 7 ) redirecting the axial drive force transferred by the screw shaft member ( 46 ) to drive a pair of claw members ( 3 ) symmetrically. Thus, the rotational drive force applied through the input shaft member ( 4 ) is increased by the worm gear mechanism ( 5 ) and the second gear mechanism ( 6 ), and this rotational drive force is redirected by the conversion mechanism ( 7 ) and transferred to the claw members ( 3 ), allowing a workpiece or tool to be firmly chucked.

TECHNICAL FIELD

[0001] The present invention relates to a chuck device. Morespecifically, the present invention relates to a chuck device equippedwith a gear mechanism that increases rotational drive force appliedthrough an input member.

BACKGROUND TECHNOLOGY

[0002] Conventionally, in machine tools such as milling machines,lathes, and machining centers, a chuck device is used to secure aworkpiece to a table, work pallet, or the like, or to mount a tool tothe principle axis, or the like. A chucking device essentially includesa base member secured to a table, a work pallet, a primary axis, or thelike, and a claw member movably mounted on this base member. This clawmember is moved so that the workpiece or tool is chucked.Conventionally, one-claw chuck devices with a single claw member,two-claw chuck devices with two claw members, and three-claw chuckdevices with three claw members have been used practically.

[0003] Referring to FIG. 9, for example, a chuck device 100, used tosecure a workpiece Wa, includes a base member 101, a claw member 102, aninput shaft member 103, a conversion mechanism 104, and a hydrauliccylinder (not shown in the figure). A leg 102 a of the claw member 102slidably engages with a T-shaped groove 101 a formed on the base member101. The input shaft member 103 extends from inside the base member 101and projects from the side opposite from the claw member 102. The outerend is connected to the hydraulic cylinder.

[0004] The conversion mechanism 104 includes: a conversion member 105secured to the input shaft member 103; a sloped engagement groove 105 aformed on the conversion member 105 with a T-shaped cross-section shapeand sloped relative to the direction of motion of the claw member 102;and an engagement section 102 b disposed on the claw member 102 toslidably engage with the sloped engagement groove 105 a. The hydrauliccylinder drives the input shaft member 103 and the conversion member 105in the axial direction, and this axial drive force is redirected by theconversion mechanism 104 and transferred to the claw member 102, causingthe claw member 102 to move in the direction of the arrow a.

[0005] Referring to FIG. 10, a chuck device 110 implemented by thepresent applicants includes a base member 111, a claw member 112, aninput member 113, and a conversion mechanism 114. A leg 112 a of theclaw member 112 slidably engages with a T-shaped groove 111 a formed onthe base member 111. The input member 113, formed as a bolt, is screwedinto the base member 113, and a rotational drive force is appliedmanually to the input member 113 using a rotation tool 119.

[0006] The conversion mechanism 114 includes: a conversion member 115into which the shaft of the input member 113 is inserted and whichengages with the head of the input member 113; a sloped surface 115 aformed on the conversion member 115 and sloped relative to the directionof movement of the claw member 112; a sloped surface 112 b formed on theclaw member 112 to form a planar contact with the sloped surface 115 a;and a compression spring 116 elastically biasing the claw member 112toward the input member 113. If the input member 113 is rotated in thetightening direction, the conversion member 115 is driven downward, andthe claw member 112 is moved in the direction of the arrow b via theconversion mechanism 114, thus securing the workpiece W. If the inputmember 113 is rotated in the loosening direction, the biasing force ofthe compression spring 116 causes the claw member 112 to move in thedirection of the arrow c.

[0007] In conventional chuck devices, the drive force applied throughthe input member can be increased (multiplied) by a conversion mechanismto drive a claw member. However, the increase in drive force appliedthrough the input member is limited if only sloped engagement groovesand sloped surfaces are used in the conversion mechanism for increasingdrive force. This makes it difficult to provide a high force increaseratio (multiplication rate).

[0008] As a result, with chuck devices in which an input member ismanually driven, the workpiece or tool cannot be firmly chucked. Thiscan lead to reduced machining precision and damage to cutting tools.Thus, firmly driving the input member manually results in reduced easeof use and lowers the efficiency of the chucking operation. Also,repeating this chucking operation will lead to fatigued arms and hands.With chuck devices that drive the input member using an actuator such asa hydraulic cylinder, the actuator makes the chuck device larger andincreases production costs.

[0009] However, increasing the slopes of the sloped engagement grooveand the sloped surface of the conversion member in the conversionmechanism can improve the rate at which the drive force is increased.However, the ratio of the displacement of the claw member to thedisplacement of the conversion member becomes very small. This limitsthe size of the workpiece, tool, or the like that can be chucked, thusreducing its versatility.

[0010] The object of the present invention is to provide a chuck devicethat can improve the increase rate of the applied drive force. Anotherobject of the present invention is to provide a chuck device thatimproves usability and increases the efficiency of chucking operations.Yet another object of the present invention is to provide a chuck devicethat can be designed compactly. Yet another object of the presentinvention is to provide a highly versatile chuck device.

DISCLOSURE OF THE INVENTION

[0011] The present invention provides a chuck device for chucking aworkpiece or a tool by moving a claw member. The chuck device includes abase member and at least one claw member movably mounted on the basemember. The chuck device also includes: an input member for applying arotational drive force; a gear mechanism using a rotational drive forceapplied through the input member to drive a screw shaft member in anaxial direction; and a conversion mechanism redirecting an axial driveforce transferred through the screw shaft member and driving a clawmember.

[0012] When rotational drive force is applied through the input member,the rotational drive force drives the screw shaft member in the axialdirection via a gear mechanism. The axial drive force transferred to thescrew shaft member is redirected by a conversion mechanism andtransferred to the claw member, moving the claw member. The gearmechanism allows the rotational drive force applied through the inputmember to be significantly increased and transferred to the screw shaftmember.

[0013] Since the drive force applied to the input member can bemultiplied significantly and transferred to the claw member, a workpieceor tool can be firmly chucked by the claw member by applying arelatively small drive force to the input member. This improves theefficiency of chucking operations.

[0014] If an actuator is used to drive the input member, a relativelysmall actuator can be used, thus allowing the chuck device to be compactand reducing production costs.

[0015] A high drive rate increase ratio can be provided withoutexcessively increasing the ratio of the displacement stroke of the screwshaft member or the like to the displacement stroke of the claw member.

[0016] In the chuck device described above, the gear mechanism caninclude a worm gear mechanism for slowing down the rotational driveforce applied through the input member and a second gear mechanism thatuses the rotational drive force transferred from the worm gear mechanismto drive the screw shaft member in an axial direction. In this chuckdevice, the worm gear mechanism significantly increases the rotationaldrive force applied to the input member. The rotational drive forceincreased by the worm gear mechanism is further increased by the secondgear mechanism, which transfers the drive force to the screw shaftmember, driving it in the axial direction.

[0017] It would be desirable for the conversion mechanism to include: aconversion member secured to the screw shaft member and not rotatingrelative to the base member; a sloped engagement groove formed on theconversion member and sloped relative to a direction of motion of theclaw member; and an engagement section disposed on the claw member andslidably engaging with the sloped engagement groove. When the screwshaft member is driven in the axial direction, the conversion mechanismdrives the conversion member integrally with the screw shaft member,changing the engagement position of the engagement section in the slopedengagement groove. As a result, the drive force in the axial directionfrom the screw shaft member is multiplied and transferred to the clawmember.

[0018] The chuck device can be formed in the following manner. A pair ofclaw members are disposed facing each other, legs of the claw membersare slidably engaged with a shared engagement groove formed on the basemember, and the conversion mechanism is formed to move the pair of clawmembers symmetrically. Alternatively, a single claw member can bedisposed on the chuck device.

[0019] The input member of the chuck device can be driven manually.Alternatively, a small electrical or hydraulic actuator can be used todrive the input member.

BRIEF DESCRIPTION OF THE DRAWINGS

[0020]FIG. 1 is a perspective drawing of an embodiment of the presentinvention.

[0021]FIG. 2 is a plan drawing of a chuck device.

[0022]FIG. 3 is a front-view drawing of a chuck device.

[0023]FIG. 4 is a vertical cross-section drawing of a chuck device (in achucked state).

[0024]FIG. 5 is a vertical cross-section drawing of a chuck device (inan unchucked state).

[0025]FIG. 6 is a cross-section drawing along the VI-VI line in FIG. 4.

[0026]FIG. 7 is a vertical cross-section drawing of a conversion member.

[0027]FIG. 8 is a plan drawing of a conversion member.

[0028]FIG. 9 is a vertical cross-section drawing of a chuck deviceaccording to a conventional technology.

[0029]FIG. 10 is a vertical cross-section drawing of a chuck deviceaccording to another conventional technology.

PREFERRED EMBODIMENTS OF THE INVENTION

[0030] Referring to the figures, the following is a description of anembodiment of the present invention.

[0031] This embodiment is an example of the present inventionimplemented in a two-claw chuck device equipped with a pair of clawmembers disposed symmetrically. These claw members are moved to chuck aworkpiece, securing it to the table of a machine tool or the like.

[0032] Referring to FIG. 1 through FIG. 6, a two-claw chuck device 1includes a base member 2, left and right claw members 3, input shaftmembers 4, a worm gear mechanism 5, a second gear mechanism 6, and aconversion mechanism 7. With this chuck device 1, the input shaft member4 is rotated manually so that the drive force is transferred to the leftand right claw members via the worm gear mechanism 5, the second gearmechanism 6, and the conversion mechanism 7, thus moving the claws 3symmetrically.

[0033] Referring to FIG. 1 through FIG. 6, the base member 2 forms awide rectangular shape when seen from above. The base member 2 includesan upper block 10 and a lower block 20 formed integrally thereto. Thelower block 20 is formed slightly wider than the upper block 10. Theclaw members 3 are movably mounted on the upper surface (upper surfacesection) of the upper block 10. Four bolt holes 2 a are formed at thecorner areas of the lower block 20. Four bolts (not shown in thefigures) inserted into these bolt holes 2 a secure the base member 2 tothe table of the machine tool (not shown in the figure) or the like.

[0034] An engagement groove 11 having a roughly T-shaped cross-sectionshape is formed on the upper block 10 extending along the left-rightaxis. Legs 30 of the pair of claw members 3 are slidably engaged withthis shared engagement groove 11. The upper block 10 is formed with alowered section 12 via a shelf 12 a at the central section along theleft-right axis. A vertical hole 13 communicating with the engagementgroove 11 is formed extending downward from the lowered section 12.

[0035] The pair of claw members 3 are formed symmetrically to the leftand the right. Each claw member 3 includes: the leg 30; a main claw unit31 disposed above the leg 30; and an engagement section 52 disposed atthe end of the leg 30 toward the lowered section 12. The main claw unit31 is formed from front and rear claw sections 31 a extending upwardfrom the upper end of the leg 30. A groove 31 b is formed inside themain claw unit 3, surrounded by the claw sections 31 a and the upper endof the leg 30. The front and rear claw sections 3 a extend parallel toeach other along the left-right axis. The upper ends of the front andrear claw sections 3 a of the left and right claw members 3 face eachother and the facing ends of the left and right claw sections 31 a serveto chuck a workpiece W disposed on the lowered section 12 by supportingit from both ends.

[0036] A horizontal hole 21 on the right side of the lower block 20 ofthe base member 2 extends from the front to the rear. A vertical hole 22extends from the bottom of the lower block 20 at the central areathereof. The right end of the vertical hole 22 communicates with thehorizontal hole 21. A vertical hole 23 is formed upward from the upperend of the vertical hole 22, and the vertical hole 23 communicates withthe vertical hole 13. A pair of covers 24 are fitted into the front andrear ends of the horizontal hole 21, and a cover 25 is fitted into thebottom of the vertical hole 22.

[0037] Referring to FIG. 1 and FIG. 3 through FIG. 6, the input shaftmembers 4 is a member used to input rotational drive force. The frontand rear input shaft members are disposed in the horizontal hole 21 ofthe base member 2. Each input shaft member 4 is fitted in and rotatablysupported by the cover 24. A worm gear 40 of the worm gear mechanism 5is disposed in the horizontal hole 21. The inner ends of the input shaftmembers 4 are inserted into the worm gear 40, and the input shaftmembers 4 are linked to the worm gear 40 via a key member 26 in a mannerthat prevents rotation relative to each other.

[0038] An angular hole 4 a, e.g., a hexagonal hole, is formed at theouter end of the input shaft member 4. The end of a rotation tool suchas a hexagonal wrench is engaged with the angular hole 4 a, and theinput shaft member 4 is manually rotated via this rotation tool to inputrotational drive force. The input shaft member 4 is prevented fromslipping out by the cover 24.

[0039] Referring to FIG. 4 through FIG. 6, the worm gear mechanism 5 isa mechanism for increasing drive torque by slowing down the rotationaldrive force input via the input shaft member 4.

[0040] The worm gear mechanism 5 is mounted inside the base member 2.This worm gear mechanism 5 includes the worm gear 40, which rotatesintegrally with the input shaft members 4, and a worm wheel 41, whichmeshes with the worm gear 40. The worm wheel 41 is disposed inside thevertical hole 22 of the base member 2, and is rotatably supported by thebase member 2 and the cover 25 while being prevented from moving alongits axis. The worm wheel 41 is rotatably fitted and screwed to a screwshaft member 46 of the second gear mechanism 6.

[0041] Referring to FIG. 4 and FIG. 5, the second gear mechanism 6 is amechanism for driving the screw shaft member 46 axially using therotational drive force transferred from the worm gear mechanism 5.

[0042] The second gear mechanism 6 is mounted in the base member 2. Thissecond gear mechanism 6 includes a threaded hole 45 formed concentric tothe center of the worm wheel 41 and the screw shaft member 46 screwed tothe threaded hole 45. A bolt 47 is inserted from below into the centerof the screw shaft member 46, and the threaded section of the bolt 47projecting upward from the screw shaft member 46 is linked to aconversion member 50 of the conversion mechanism 7 so that the screwshaft member 46 and the conversion member 50 are linked in a fixedmanner.

[0043] A collar member 48 is secured between the screw shaft member 46and the head of the bolt 47. This collar member 48 has a diameter thatis slightly less than that of a hole 25 a of the cover 25. When thescrew shaft member 46 is in a lowered state, the collar member 48 fitsinto the hole 25 a, and the axial center of the screw shaft member 46and the rotational center of the worm wheel 41 are placed in fixedpositions.

[0044] Referring to FIG. 1, FIG. 2, FIG. 4, and FIG. 5, the conversionmechanism 7 changes the direction of the axial drive force transferredby the screw shaft member 46 and transfers this force to the pair ofclaw members 3, moving these left and right claw members 3symmetrically. This conversion mechanism 7 includes the conversionmember 50, a sloped engagement groove 51, and a pair of engagementsections 52.

[0045] The conversion member 50 is secured to the screw shaft member 46by the bolt 47. This conversion member 50 is disposed within thevertical holes 13, 23 of the base member 2. The conversion member 50 isformed with a pair of T-shaped sloped engagement groove 51 sloped in thedirection of movement of the claw members 3. The pair of claw members 3are formed with a pair of engagement sections 52 to slidably engage withthe pair of sloped engagement grooves 51. Since the pair of engagementsections 52 engage with the pair of sloped engagement grooves 51, theconversion member 50 is prevented from rotating relative to the basemember 2.

[0046] Referring to FIG. 7 and FIG. 8, the sloped engagement grooves 51are sloped at approximately 70 degrees relative to the direction ofmotion of the claw members 3 (the horizontal direction) so that thelower the grooves are, the further they are from the axial center of theconversion member 50. The lower the conversion member 50 and the screwshaft member 46 go, the closer the pair of claw members 3 approach eachother. Conversely, the higher the conversion member 50 and the screwshaft member 46 are, the further apart the pair of claw members 3 move.The legs 30 of the claw members 3 are formed with grease holes 3 a.Grease in these grease holes 3 a is fed between the sloped engagementgrooves 51 and the engagement sections 52.

[0047] The operations and advantages of the two-claw chuck device 1 willbe described.

[0048] Referring to FIG. 5, when chucking the workpiece W, theconversion member 50 is first moved upward so that there is adequatespace between the pair of claw members 3. The workpiece W is then setonto the lowered section 12. Referring to FIG. 5, the conversion member50 is moved to the uppermost position and the pair of claw members 3 arepositioned so that they are separated by the maximum distance. However,when setting the workpiece W, the pair of claw members 3 does notnecessarily need to be separated by the maximum distance.

[0049] Next, the end of a rotation tool such as a hexagonal wrench isengaged with the angular hole 4 a of the input shaft member 4, and theinput shaft member 4 is manually rotated with the rotation tool so thatthe pair of claw members 3 move toward each other. In the worm gearmechanism 5, the worm gear 40 rotates integrally with the input shaftmember 4, and the worm wheel 41 meshed with the worm gear 40 rotatesaround the vertical axis.

[0050] In the second gear mechanism 6, the worm wheel 41 cannot movevertically when the worm wheel 41 is rotated, so the screw shaft member46 screwed to the threaded hole 45 of the worm wheel 41 is drivendownward, and the conversion member 50 secured to the screw shaft member46 is driven downward as well.

[0051] In the conversion mechanism 7, when the conversion member 50moves downward the operation of the sloped engagement grooves 51 of theconversion member SO and the pair of engagement sections 52 cause thepair of claw members 3 to come closer, i.e., move toward the workpieceW. As shown in FIG. 4, the upper ends of the claw sections 31 a of thepair of claw members 3 firmly chuck the workpiece W from the left andright. Machining is then performed on the workpiece W from this chuckedstate.

[0052] When removing the workpiece W, the rotation tool is used torotate the input shaft member 4 in the opposite direction so that theclaw members 3 move away from each other. The rotation causes the screwshaft member 46 to move upward via the worm gear mechanism 5 and thesecond gear mechanism 6. This causes the conversion member 50 secured tothe screw shaft member 46 to move upward as well, driving the clawmembers 3 away from each other via the conversion mechanism 7. Thisreleases the chucked state.

[0053] According to this chuck device 1, the worm gear mechanism 5allows the rotational drive force input through the input shaft member 4to be significantly increased (multiplied). Furthermore, the second gearmechanism 6 increases the rotational drive force transferred from theworm gear mechanism 5 and transfers it to the screw shaft member 46,driving the screw shaft member 46 in the axial direction. The axialdrive force transferred by the screw shaft member 46 is redirected andincreased by the conversion mechanism 7 and is transferred to the pairof claw members 3. This causes the claw members 3 to move symmetrically.

[0054] By providing the worm gear mechanism 5, the second gear mechanism6, and the conversion mechanism 7 as described above, the drive forceinput through the input shaft member 4 can be increased in three stagesand then transferred to the pair of claw members 3. As a result, simplyapplying a manual drive torque to the input shaft member 4 can firmlychuck the workpiece W. As a result, the usability of the chuck devicecan be improved and chucking operations on the workpiece W can be mademore efficient, thus preventing reduced machining precision and damageto cutting tools.

[0055] A high ratio for increasing the drive force can be provided evenwithout a very large ratio between the displacement stroke of the clawmembers 3 and the displacement strokes of the conversion member 50 andthe screw shaft member 46.

[0056] Since the pair of claw members 3 is mounted on the upper surfaceof the base member 2 and the worm gear mechanism 5 and the second gearmechanism 6 are mounted inside the base member 2, the structure forincreasing the drive force can be made compact. Also, entry of debrisinto the gear mechanisms 5, 6 can be prevented.

[0057] Since the claw members 3 are disposed facing each other and thelegs 30 of the claw members 3 are slidably engaged with the sharedengagement groove 11 formed in the base member 2, the shared engagementgroove 11 can reliably guide and support the claw members 3 along theiraxis of motion. As a result, the workpiece W can be reliably chucked bybeing supported from either side by the claw members 3.

[0058] Next, examples of partial modifications to the above embodimentwill be described.

[0059] 1) The worm gear mechanism 5 can be omitted. If this is done, arotation member is provided to substitute for the worm wheel 41, and thescrew shaft member 46 is screwed into a threaded hole formed in thisrotation member. Some sort of input member to input rotational driveforce can be provided to rotate this rotation member, so that the screwshaft member 46 is driven axially.

[0060] 2) Instead of the pair of claw members 3, a single claw membercan be provided, and the workpiece can be chucked by supporting itbetween the claw member and a receiving section of the base member.Alternatively, three claw members can be provided, and the workpiece canbe chucked using these three claw members. Changes in the number of clawmembers can be easily handled simply by changing the number andpositions of the sloped engagement grooves formed on the conversionmember in the conversion mechanism.

[0061] 3) The input shaft member 4 can be rotated by an actuator such asa motor to apply rotational drive force through the input shaft member4. Since rotation of the input shaft member 4 does not require a highdrive force, the actuator can be compact, thus allowing the chuck deviceto be compact and reducing production costs.

[0062] 4) An upper plate, used to chuck the workpiece by supporting itin cooperation with one of the claw members 3, can be secured to thelowered section 12 using bolts screwed into the lowered section 12. Inthis case, the other claw member 3 would not be used. However, bymounting the upper plate for workpieces having certain shapes, it wouldbe possible to chuck workpieces smaller than the workpieces W chucked bythe pair of claw members 3. Furthermore, after the upper plate ismounted, the upper plate can be cut into a shape corresponding to theshape of the workpiece using machine tools or the like. This providesreliable chucking for different workpiece shapes.

[0063] 5) Various other modifications may be effected without departingfrom the spirit of the present invention. Also, the present inventioncan be used in chuck devices that secure the work piece to a rotatingbody of a machine tool or that secure tools to the principle axis.

[0064] Possible Uses in Industry

[0065] With the chuck device according to the present invention asdescribed above, a light manual drive force can be applied to drive theclaw members forcefully and provide firm chucking of workpieces or thelike. Thus, a compact and high-performance chuck device for providingworkpieces and tools is provided, and chucking operations can be mademore efficient.

1. In a chuck device, including a base member and at least one clawmember movably mounted on said base member, for chucking a workpiece ora tool by moving said claw member, a chuck device comprising: an inputmember for applying a rotational drive force; a gear mechanism using arotational drive force applied through said input member to drive ascrew shaft member in an axial direction; and a conversion mechanismredirecting an axial drive force transferred through said screw shaftmember and driving a claw member.
 2. In a chuck device, including a basemember and at least one claw member movably mounted on said base member,for chucking a workpiece or a tool by moving said claw member, a chuckdevice comprising: an input member for applying a rotational driveforce; a worm gear mechanism slowing down a rotational drive forceapplied through said input member; a second gear mechanism using arotational drive force transferred from said worm gear mechanism todrive a screw shaft member in an axial direction; and a conversionmechanism redirecting an axial drive force transferred through saidscrew shaft member and driving a claw member.
 3. A chuck device asdescribed in claim 2 wherein: said worm gear mechanism includes a wormgear rotating integrally with said input member and a worm wheel meshingwith said worm gear; and said second gear mechanism includes a threadedhole formed concentrically with a center of a worm wheel and said screwshaft member screwed into said threaded hole.
 4. A chuck device asdescribed in claim 2 wherein said conversion mechanism includes: aconversion member secured to said screw shaft member and not rotatingrelative to said base member; a sloped engagement groove formed on saidconversion member and sloped relative to a direction of motion of saidclaw member; and an engagement section disposed on said claw member andslidably engaging with said sloped engagement groove.
 5. A chuck deviceas described in any one of claim 2 through claim 4 wherein: a pair ofclaw members are disposed facing each other; legs of said claw membersare slidably engaged with a shared engagement groove formed on said basemember; and said conversion mechanism is formed to move said pair ofclaw members symmetrically.
 6. A chuck device as described in any one ofclaim 2 through claim 5 wherein: said claw member is mounted on an uppersurface of said base member; and said worm gear mechanism and saidsecond gear mechanism are mounted in said base member.
 7. A chuck deviceas described in any one of claim 2 through claim 6 wherein rotationaldrive force is applied manually to said input member.